Google Inc. (NASDAQ:GOOG) is still investigating an apparent Gchat glitch that alarmed Google Hangout users in the wee hours of the night. Late Wednesday, users began reporting that the instant-message service was malfunctioning by sending chat messages to the wrong people. Private messages meant for certain recipients went to someone else or, in some cases, multiple people. Some Gchat users, mystified by the mix-up, posted about the security glitch on Twitter.

According to Google, the glitch affected messages sent between 10:00 p.m. and 1:30 a.m., PST. Messages sent after that time did not appear to be affected, the company said on its Service Details page.

It’s unclear what caused the malfunction, which is particularly troubling in light of ongoing privacy concerns regarding Google products and other cloud-based services. Some Twitter users joked about the glitch in the context of the NSA surveillance scandal.

Man, the NSA must be pissed. All their gchat CC's are going to random people today!

Gchat is the colloquial name of Google Talk, an instant-message service first launched in 2005. The service is often used among friends and coworkers who wish to have private conversations during working hours.

Google said it plans to post an update at 12:00 p.m., PST, detailing when it expects to resolve the Gchat issue. Updates will be posted here.